- INTRODUCTION
- Leaching is a condition where liquids ooze out of the joints between ceramic
tile veneer regardless of whether or not the veneer is grouted, and runs down
over the tile.
- The reference to ceramic tile veneer pertains to all types of tile used for
tiling the exterior walls of buildings including the brick-like tile.
- Sometimes this leaching is called efflorescence, but it is not. Efflorescence
is a deposit of soluble salts, usually it is white in color. Efflorescence is
formed when water penetrates, picks up the soluble salts, brings them to the surface
where they are left when the water evaporates.
- Efflorescence is comparatively easy to remove, especially when additional
water is prevented from penetrating the structure and the efflorescence dries
and can be brushed away with a dry bristle brush. The liquid that leaches out
of the joints is not easy to remove.
- The stain is difficult to remove when it first occurs and the longer it is
left on the tile the more difficult it is to remove. Even after the cleaning is
done, there is a tendency for the run down marks to still show.
- DISCUSSION
- This leaching occurs on glazed tile just as readily as it does on unglazed
tile, and it is just as difficult to remove from the glazed surface.
- Most successful removal is done by cleaning companies using high pressure
chemical cleaning equipment with capabilities of heating the cleaning water. It
takes the force of the hot water and chemicals to hit the surface with the needed
impact to remove the residue from the leaching and the stain.
- Coatings on the tile used as grout releases may make the tile easier to clean
but may also become a problem. Some of these coatings will turn white after exposure
to the elements and then they are difficult to remove.
- Rain is one of the biggest contributors to the leaching problem. The leaching
from the rain is most damaging on partly constructed buildings where covers have
not been installed on the top of the parapet walls.
- A second source of water occurs when the tile veneer is bonded directly to
concrete or masonry. When concrete and masonry mortars cure they must give off
water, and this dispelled water must find its way to the surface. The water works
its way through the grout joints and contributes to the leaching problem.
- When either rain water, or the dispelled water, comes in contact with freshly
placed latex bonding mortar, the latex can be activated and leach out of the installation.
There are several different types of latex that are used in bonding mortars. When
latex bonding mortars are freshly placed all types of latex are water sensitive.
Latex bonding mortars can be designed so that they do not leach out, but this
ability of not leaching becomes a reality only after the latex has cured out.
When the latex cures out it forms a film and once the film forms on latex designed
not to leach it will not leach.
- If the latexes are subject to leaching from heavy rain, then the latexes would
also be of concern in swimming pools, fountains and reflection pools. Being covered
with water the latexes may not show stains from leaching but would lose their
bond strength if not completely cured out.
- CONCLUSION
- If exterior tile is installed using latex bonding mortar during rainy weather,
leaching is very likely to occur. If the rain water is allowed to pour down into
walls where the parapet is not capped, the leaching will be worse.
- Latex can be designed to prevent leaching but only after the latex is cured
out by forming a film.
- All latexes are not designed to not leach.
- If leaching does occur, obtain the services of a cleaning company experienced
in cleaning the leaching off of the tile.
- If latex mortar is used in swimming pools, fountains or reflection pools,
be sure they are completely cured out prior to filling them with water.
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